Hitherto, as a typical example of dyeing methods using coloring matters extracted from natural plants to dye textiles, such as threads and cloths, there is known dyeing with vegetable dyes, in which a decoction extracted by decocting roots, stems, barks, leaves, flowers, fruits/seeds, etc. of various natural plants is employed as a dye bath. With the dyeing with vegetable dyes, however, because an adsorption rate of the coloring matters is low, a dyeing step has to be repeated or performed by a method using a mordant and a catalyst in order to reproduce the desired color. Further, a very long time is required for the dyeing step, and the fastness of color against washing is also not so high.
In view of such a situation, there is proposed a technique for pulverizing a natural material, from which a coloring matter is to be extracted, into powder of 20 to 30 microns, dispersing the powder in a prepared solvent, filtering the disperse solution to obtain, as a dye bath, a filtrate from which the powder has been removed, and dyeing a cellulose-base textile material in the dye bath (see, e.g., Patent Document 1). Thus, the proposed technique is intended to increase extraction efficiency of the coloring matter from the natural material by pulverizing the natural material into the powder of 20 to 30 microns.
Patent Document 1: JP, A 11-124778